Greenhouse heating system



oct. 21, l195s J. o, WALLACE GREENHOUSE HEATING SYSTEM Filed oci. 18,1954 INVENTOR. JAMES 0 WALLACE ATTORNEY .M fa

AVV2,857,108 l GREENHOUSE HEATING SYSTEM James T: Wallace,` Southl San."Francisco, Calif. YApplication October 1'8, 1954,7Serial No. 462,779

11 Claim. (Cl.-2'37-"53) The invention, inV general, relates totheheatingand air conditioning art andmore particularlyrelates -to .asystem for maintaining .-a .uniform hot or Iwarm temperature throughoutthe entire 'interior of greenhouses despite colder temperaturesoutsideof the greenhouse.

Heretofore there have been attempts to provideequip- .ment capable of.vmaintaining desired temperature conditions-within a-greenhouse; suchequipment usually comprising yan underground mainfduct for conveyingYheated air=to andi through a-series of vduct-communicating riserslocated at random; positions withinthe `greenhouseforemittingftheheated-airfabove thetops of plants. These prior systemshave' been found disadvantageous because of the rapidl dissipationnofthe-transmitted air I.at isolated .spots or areas, -whieh'results fromthe diminishing pressures behind the heatedairthroughout the main ductVvand the risers of lthe system. '-Uniformity rof `temperaturethroughout` thefgreenhouse, therefore, is not attainedfby such. priorlequipment. The presentinventionv is directed to obviating inherentdisadvantages'of f prior greenhouse heating systems and :the provision:of `relatively `simple elements for effecting .proper greenhouseheating.

Theprimary objectofthe present invention is to provide animprovedgreenhousefheating system wherein heated..air under effective`pressures is uniformly distributed overtthe .entire interior ofragreenhouse.

Another-:object of my inventionris to vprovide an improved greenhouseheating Systemy of the indicated nature which-ist-additionallycharacterized by the .incorporation therein of a mainsectionalfduct-vfor distributingfheated air under uniform pressure ateifective angular directions to the plants in the greenhouse.

A still further object of mypresent invention is to provide an improvedgreenhouse heating system of the aforementioned character wherein .themain sectional 'duct isftapered, -section to section, permittingready'shipping and storage .thereof in nested condition.

Another object of the vinvention-,is toprovidelanlimvproved greenhouseheatingsystem whichk is installblel at low cost and which can bemaintained at a minimum of expense.

Other objects of the invention, together with some of the advantageousfeatures thereof, will appear from the following description of apreferred embodiment of my invention which is illustrated in theaccompanying drawings. It is to be understood, however, that I am not tobe limited to the precise embodiment shown, nor to the precisearrangement of the Various parts thereof, as my invention, as dened inthe appended claims, can be ernbodied in a plurality and variety offorms.

Referring to the drawings:

Fig. 1 is a fragmentary elevational view of a pre ferred embodiment ofthe present invention, the sectional duet being broken for purposes ofillustration; this View illustrating the system installed in butone-half of the length of a standard greenhouse.

Fig. 2 is a sectional view taken through a nested group arent 2,857,108.Patented Oct. 21, 1958 'ice . 12 oftube sections of "the preferredembodiment of the invention.

Fig. 3. is afragmentary elevational view illustrating thesupportingmeans for the 'duct sections ofthe preferred embodiment of theinvention.

:In its preferred form,.`the improved `greenhouse heating system of mypresentinvention,preferably comprise a furnace disposed' in Ltheapproximate .f center `of av greenhouse rfor producing a `tlow fheateduid under vprede- `terminedpressure, and' means in communication withythe outlet of said" furnace for'distributing the produced heated fluidun'der substantially.saidrpredetermined pressure over vthe, plants andother growth throughout thegreenhouse.

.As particularly illustratedfin .Fig 1 of the annexeddrawings,`Igprovide a furnace llwhich -is set up at approximatelythecenter o`f a standardgreenhouse which usually has'the dimensions of`approximately l00`feet in length and30'feet in width. Theffurnace 11,in thepre- .ferred `embodiment of `the.invention, is supported on legs'12 'resting upon aconcrete'founlation 13, thus providing :aspace'14betweenlthefoundation and the open' bottom,

whichis in communication with the outlet, not shown,of

the furnace; .the plenum being hollow and beingY provided with -aplurality f outlets' 18. inthe sides' thereof. Firing of the`furnace 11will causelthe production of a flowof 'heatedfluidun'derLa predeterminedpressure at`its outlet whichmoveslinto the" head 17` 'thereof `fordistribution.

"In accordance with my present invention, yl provide meansforvldistr'ibut'ing theheateduid produced bythe furnace" 11thrOUghOUt'thelength and width of the. greenhouse, not shown, inwhich"thef'furnace'isdisposed and under substantially,,predeterminedpressure at which the 'fluidfowiis `emitte`d..f1"onithe furnace.Thesemeans `preferably comprise, a plurality o'ffducts which .are4similar in. character andof which but one4 is shown inthe annexedAdrawingsfor' brevity of description and simplicityoffillustration,usuch 'ductbirig generally designated by the reference numeral. 21."Du'ct21 is supported at an elevation fromlthe'ioor ongroun'd surface ofthe greenhouse, andthis 'support usu'llyL is provided by; the ,crotchesfbetween y"the standards; and i braces, see "'Fig. v3, .supporting ltheAroofl and side-walls .of "the greenhouse "By so. supporting"the-duct21, 'the' bottom `Z2 `of Vthe duct will .lie horizontally orf parallelto the "oor orI ground. surfaceof 'the greenhouse and the 'iiiletend-.'23 of the` duct 21 is 'placedfin communication 'with one 'side.outlet18 .ofthe plenumf17'wlrer`eby duct"21"extends longitudinally andfor approximately onehalf of the length of the greenhouse. It is to beunderstood that another duct, not shown but similar in all respects toduct 21 and similarly supported, is placed in communication with anotheroutlet 18, not shown, of the plenum 17 diametrically opposite to theplacement of duct 21; this latter mentioned duct extending in theopposite direction longitudinally of and for approximately the remainingonehalf of the length of the greenhouse. Thus, for a greenhouse of feetlength and 30 feet width, the furnace 11 is located at the approximatecenter of the greenhouse and two ducts 21 of approximately 42, feet inlength each, extend from plenum 17 of the furnace in opposite directionslongitudinally of the greenhouse. Itis to be understood, of

, are true cylindrical tubes.

feet points measured from a given end of the greenhouse,

and four ducts similar to illustrated duct 21 are utilized; two for eachfurnace and in the arrangement described above. Moreover, transverselyextending ducts ofsimilar type but'ofshorte'r length are placed incommunication with theplenums ofthe furnacesfor distributing the heatedfluid over the widths of such wider greenhouses.

As illustrated in Figs. 1 andV 2, the duct 21 is detachably secured byany suitable means such as metal screws,

Vnot shown, to ashort cylindrical section'23 communicating with sideoutlet 18 of the plenum 17 and in which section 23 a suitable dampermeans 24, such as a quadrant damper, is installed for regulating fluidow. The'duct 21 comprises aplurality of sections of which but nine areshown in the accompanying drawings designated by the reference numerals26 to 34 inclusive; such duct sections alternately constitutingirregular and regular cylindrical tubes in that the irregular sections26, 28, 30, 32 and 34, commencing with section 26 connected to shortcylindrical section 23 adjacent to plenum 17, all are tapered onV theirtops and are straight on their bottoms while the intermediate regularcylindrical sections 27, 29, 31 and 33 Moreover, the duct 21 is ofdiminishing cross-section from the plenum 17 outwardly to the terminusof the duct and each of the sections 26 to 34 inclusive is formed with aplurality of port openings 36, 37, 38 and 39 therein which are inopposite sides thereof, arranged in staggered relationship side to side,as indicated by the full and dotted line showings of Fig.

l of the drawings, and which are all below the transverse diameters ofthe sections as clearly shown in Fig. 2. It is to be noted that the portopenings 36 to 39 inclusive of the duct sections of duct 21 preferablyare circular and preferably all of the same diametersl for allof theduct sections regardless of the diminution in cross-section of the ductsections outwardly from the furnace 11. That is to say, the portopenings 36 to 39 inclusive of duct section 26 are circular and of thesame diameter, say 3 inches and the diameters of the port openings 36 to39 inclusive of the remaining duct sections all are of the samediameters, i. e., 3 inches.

By such duct construction, with the sections of diminishingcross-section outwardly from the furnace 11, the produced heated Huidfrom the furnace ll'will be conveyed throughout the entire length of theduct 21 for emanation not only through the end of the last section 34 ofthe duct but also from all of the port openings 36 to 39 inclusive ofeach duct section under substantially the same pressure as' delivered bythe furnace 11. Moreover since the port openings 36 to 39 inclusive ofall of the duct sections are all below the transverse diameters of thesections, the heated fluid will be downwardly directed from both sidesof the duct all along the length thereof and, therefore, effective heattreatment of greenhouse plant growth' is attained. The same constructionof duct sections obtains for the oppositely directed duct abovementioned in connection with a standard greenhouse of 100 feet lengthand 30 feet width, as well as to all ducts employed in largergreenhouses. Accordingly, cold air drawn through the bottom of thefurnace 11 is heated by the furnace and caused to be `delivered underpressure out through furnace plenum 17 and to the duct 21 from which itis downwardly directed from all port openings 36 to 39 inclusive of allduct sections under substantially the same pressure as delivered fromthe furnace onto the plant growth and throughout the entire greenhousearea.

Since the duct sections of duct 21, as well as of corresponding ductscommunicating with furnace 11, are of diminishing cross-sectionsoutwardly from the furnace, it is clear that the sections can betelescopically tted together to provide each complete duct; the adjacent`sections being detachably fastened together by means of mentalscrews.Because of this construction of the duct 21, the sections are readilynested together for easy transportation or storage when not in use in agreenhouse, taking up but a minimum of space in transit or in storage.

It is to be understood that the appended claims are to be accorded arange of equivalents commensurate in scope with the advance made overthe prior art.

I claim:

A greenhouse heating system for maintaining a uniform warm temperaturethroughout the entire interior of a greenhouse despite coldertemperatures outside of the greenhouse, said greenhouse heating systemincluding a furnace for producing a flow of heated fluid under pressure,a horizontally disposed elongated linear duct having one end connectedwith the outlet of the furnace for transmitting the produced heatedfluid under pressure, said duct comprising a plurality of short tubularsections connected end to end and all of said tubular sections having acommon lowermost line of tangency, each of said tubular sections havinga plurality of port openings of uniform diameter in opposite sidesthereof, all located adjacent .to the line of tangency for emitting anddownwardly directing, toward the plants in the grenhouse, the heatedfluid under uniform pressure from opposite sides of all sections, theupper portions of said tubular sections being closed against escape ofheated fluid so that all heated tluid discharged from said tubularsections must be discharged downwardly by way of said port openings,said tubular sections being progressively smaller from the furnace endto the remote end, alternate tubular sections being frusto-conical inform, the remaining tubular sections being right-cylindrical in form.

References Cited in the le of this patent UNlTED vSTATES PATENTS OlsonJuly 27, 1948

